The overall aim of Subproject 2 is to determine the relationship of maladaptive behaviors with the development and progression of Alzheimer's disease (AD) in adults with Down syndrome (DS). Studies in the general population have found a spectrum ofmaladaptive behaviors that many individuals with AD display prior to onset and during its progression. The appearance of specific maladaptive behaviors in the elderly may be an early indicator of the onset of dementia. Different types of maladaptive behaviors (e.g., aggression, anxiety, and delusions) have been found to be heterogeneous, both in the type and timing of presentation during the course of AD. Clarification of the different pattems of the various types of maladaptive behaviors in relation to AD onset, and the association of specific maladaptive behaviors with different stages of AD may provide valuable insights into diagnosis, treatment for individuals with DS. Few studies have investigated the types maladaptive behaviors associated with AD in adults with DS. Our preliminary work suggests that the presentation of AD in this population may be atypical and that maladaptive behaviors may be among the earliest detectable signs of dementia onset. However, there have been no longitudinal studies conducted explicitly to determine the types of maladaptive behaviors associated with the onset of dementia and with their persistence and severity throughout the progression of AD. In this study we will determine longitudinally how maladaptive behaviors are related to dementia onset and progression and examine how maladaptive behaviors vary with the presence of specific factors such as sex, level of mental retardation and whether or not psychoactive medications are prescribed, in 338 adults with DS. The results of this study will broaden the scope of measures for screening and early detection of AD in DS and will have implications for prevention and therapeutic interventions.